[MNT] Similarity search cleanup

[baraline]

Reference Issues/PRs

N/A

What does this implement/fix? Explain your changes.

Following the decisions made after #2473 and multiple discussions, this PR aims at clarifying the goal and interface of the similarity search module, notably by removing all components related to motif discovery, in order to not mix both intents even if they are related down the line.

This introduced a unique interface for all similarity search estimator, and focus on two use cases :

• Similarity search with subsequences
• Similarity search with whole series.

Both cases take as input a 3D array (a time series collection) during fit and a 2D array (a subsequence or a whole series) during predict. The predict function returns two arrays indexes, distances that contain the indexes of the matches in the collection as well as their distances to the 2D series.

The goal is to validate this structure to be able to move the module out of experimental in the near future.

Does your contribution introduce a new dependency? If yes, which one?

No

Any other comments?

The code related to motif search has been deleted to simplify the intent and structure of the similarity search module. But a new motif search module would be a welcome addition later.

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I have added the following labels to this PR based on the title: [ maintenance ].
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